A charge-pump circuit is a type of circuit configured to provide a voltage with a high voltage level that is either more positive than a power supply voltage (referred to as a high positive voltage) or has a reverse polarity with respect to the power supply voltage (referred to as a high negative voltage). In many circuit applications, both the high positive voltage and the high negative voltage are required, and it is common for these voltages to be generated on-chip. To that end, the conventional solution is to include two distinct charge-pump circuits, one for generating the needed high positive voltage and another for generating the needed high negative voltage. The drawbacks associated with this conventional solution are: an increased area on chip that is occupied by the two distinct charge-pump circuits (more specifically with respect to the needed capacitors and resistors) and an increase in power consumption.
Depending on the magnitudes of the needed high positive voltage and high negative voltage, a multi-stage charge pump circuit may be required for each voltage generator circuit. The use of multiple stages to acquire the desired voltage magnitudes can have adverse consequences in terms reduced efficiency and reduced reliability. Additionally, separate voltage generators for generating the high positive voltage and high negative voltage require separate clock buffer circuits to drive the capacitive switching operation, and this can result in an undesirable increase in on chip current consumption.
There is a need in the art for a multi-stage charge pump circuit that addresses the foregoing and other problems to support the simultaneous generation of both a high positive voltage and a high negative voltage from a common charge pump circuit.